The Islamic Republic is expanding its reach and raising questions over U.S. ambitions to contain the country.

Nigerian carpenter Bashir Muhammad has never been to Iran, but he would fight to the death for the country.

“If Iran wants our help, we are ready to go and help it, even with our blood,” he said. “Donald Trump needs to know that Iran has followers all over the world ready to help defend it against America.”

Touring the narrow unpaved streets of Zaria in Nigeria’s predominantly Muslim north, Muhammad shows Iran’s success in building enclaves of fervent support way beyond the Middle East and the limits of any harsher foreign policy planned by the U.S. president to contain it. The 30-year-old is among an increasing number of converts to the Shiite brand of Islam that Iran has been exporting since its 1979 revolution.

As the world adjusts to the Trump era, the message for Washington and its allies is that Iran wields growing influence in unexpected places. The Islamic power has been able to expand its reach regardless of the economic sanctions that excluded it from much of the global oil market until last year.

In this case, it’s in Africa’s most populous nation, key oil producer and a country where the sectarian battle that has thrown the Middle East into chaos is festering. Nigeria’s Muslims are mainly Sunnis and Iran’s growing foothold in Africa has alarmed the Saudis.

“Iran is on its own crusade, its own global war, believing that the U.S. is out to get it,” said Paul Salem, vice president of the Middle East Institute in Washington. “They’re building networks, under religious slogans, that they can use in any fight. And wherever they are expanding, there’s a potential for a sectarian Shiite-Sunni conflict.”

Trump has signaled a sharp departure from the detente that marked the previous American administration’s relations with Iran following a landmark accord over its nuclear program in 2015. The U.S. last month put Iran “on notice” following a ballistic missile test and imposed more sanctions. Trump called the nation “the world’s top sponsor of terrorism.” Steve Bannon, Trump’s chief strategist, has said there’s a “global existential war” between some parts of the Muslim world and the “Judeo-Christian West.”

The Pentagon is monitoring Iranian activities in Nigeria and West Africa, spokesman Christopher Sherwood said. Saudi cables released in 2015 by WikiLeaks reveal concern about Iran-driven Shiite expansion from Mali, Mauritania, Burkina Faso and Nigeria in West Africa to India and China in Asia.

“Certainly, the Department of Defense is always aware of Iranian activities, and I should say destabilizing activities,” Sherwood said in an interview in Washington last week. “They are a concern to us and certainly that region of the world.” Nobody could be reached at the Iranian Ministry of Foreign Affairs for comment.

Muhammad, who was born a Sunni, said he converted five years ago despite his family’s threat to kill him. Last month, it was clear where his loyalties lay. Muhammad was with a group of friends outside a local mosque in one of Zaria’s poorer neighborhoods when one of them picked up the news on his phone of Trump’s intention to take a tougher stance on Iran.

“We burst out laughing,” he said. If Iranian Supreme Leader Ayatollah Ali Khamenei “says everyone who finds an American in their country should kill him, we will kill him,” he explained as the streets filled up with girls from elementary school, their hair covered with flowing waist-length veils.

For Muhammad, the culprits are not only the Americans. It’s also their allies, Israel and Saudi Arabia. As he lashed out at those two countries, his words were a reminder of the rhetoric used by Hassan Nasrallah, the Lebanese leader of Hezbollah, which is funded and armed by Iran.

“There’s enmity between Iran on one side and the U.S., Israel and Saudi Arabia on the other side,” said Muhammad.

For the Iranians, just like the Soviet Union, the narrative reflects an existential, ideological struggle with the U.S., according to Salem at the Middle East Institute. It’s about gaining an advantage anywhere in the world that can be used now or in the future, he said. Iran uses proxy militias including Shiite Afghans, Iraqis and Lebanese to support Syrian President Bashar al-Assad against opponents, some of whom are backed by the U.S. and Saudi Arabia.

Iran’s drive into western Africa is also a direct challenge to its old Saudi enemy and the ultra-conservative strand of Sunni Islam the kingdom exports. It has created friction between communities in Nigeria as the two countries help fund religious centers that run schools and bring in students and clerics for training. In the background, is a shrinking oil-based economy, a currency at a record low and the fight against Sunni militant group Boko Haram.

To counter the Shiite expansion, the Saudi cables suggest sending more students on scholarships and increasing financial support to Islamic centers. Recently, two Saudi clerics visited the Nigerian capital, Abuja, and one of them delivered Friday prayers. He was adviser to the kingdom’s royal court.

“The Saudis watching the Iranians trying to break into northern Nigeria is almost like watching someone else try to befriend your best friend,” said Ini Dele-Adedeji, a Nigerian academic at the University of London’s School of Oriental and African Studies who specializes in Islamic identity in his home country. “On the surface, it’s about these countries helping out with ‘charitable work’ activities. But beyond that it’s also a way for those countries to almost create extensions of themselves.”

There were hardly any Nigerian Shiites in 1960, when the country gained independence from Britain. Most of the Muslims at the time were Sufis with no affiliation to any group, according to Alexander Thurston, author of “Salafism in Nigeria: Islam, Preaching and Politics.” As Saudis made investments in the early 1960s, Nigeria was one of the places they looked at and weren’t “initially motivated by competition with Iran,” he said.

Estimates vary wildly as to how many of Nigeria’s 190 million population, which is roughly divided between Christians and Muslims, are now Shiites. Some followers put their number at 20 million, while Sunnis say they’re not even a quarter of that.

It all began with a Sunni Muslim university activist, Ibrahim El-Zakzaky, who was so impressed with the Iranian revolution that he wanted one at home. When that didn’t happen, Zakzaky went to Iran, at some point he became a Shiite and later started wearing the white turban of a cleric. He became the leader of the Islamic Movement in Nigeria and turned it into a vehicle for proselytizing and gaining followers in the 1990s.

Things escalated when Nigerian troops killed more than 300 Shiites in Zaria in December 2015 and arrested Zakzaky and hundreds of his followers. The army accused the Shiite group of attempting to kill Nigeria’s army chief-of-staff, a charge the movement denies. Zakzaky remains in jail.

Muhammad, the carpenter, converted after attending two daily lectures by Zakzaky for weeks. Former newspaper vendor Sharif Abu Bakr Zakariya, 43, said he became a Shiite more than 20 years ago after the cleric “told us the truth about Islam.”

Paralyzed for the past decade, he sat in a wheelchair in a tiny room decorated with a picture of the late Ayatollah Ruhollah Khomeini, Iran’s first supreme leader. He agreed with Muhammad’s assessment of the world. “Trump is carrying out a Zionist agenda,” Zakariya said. And what if he confronts Iran? “No, he won’t be successful,” he said.

Zakariya, who lives with his wife and seven children in two rooms in a low-income neighborhood in the city of Kano, the hub of Nigeria’s Muslim north, survives on handouts from Zakzaky’s Islamic movement. He gets about 1,500 naira ($4.80) a week. He said he would offer his kids to Iran if Ayatollah Khameini said he needs them to confront America.

“I love him,” he said. “I love Iran.”

Iran has been funding Zakzaky for years and the area of Zaria he worked in became the “mecca for the dispossessed in Nigeria,” according to Matthew Page, a former U.S. State Department specialist on Nigeria. The Islamic Movement in Nigeria has been receiving about $10,000 a month, he estimated.

Zakzazy took that money and turned it into the monthly operating budget for a social welfare organization, creating a soup kitchen and homeless shelters, said Page. “This was a very inexpensive way for Iran to have a toehold in Nigeria,” he said.

The organization boasts more than 300 schools, Islamic centers, a newspaper, guards and a “martyrs’ foundation” funded mainly by member donations. The network is similar to other welfare systems established by Hezbollah and other Iranian-backed groups. Such activities in Nigeria show that reintroducing conventional sanctions on Iran won’t work, said Ghanem Nuseibeh, founder of London-based consultants Cornerstone Global Associates.

“You’re talking about a geopolitical conversion and politicizing chunks of Muslim populations around the world who have previously no relations with Iran or Shiism,” he said. “You might be able to formally increase sanctions on Iran but Iran has tentacles that go beyond its borders that are very difficult to control.”

The Nigerian government this month declared the Islamic Movement of Nigeria a security threat, comparing it with the Boko Haram insurgency, according to a Foreign Ministry statement carried by Premium Times newspaper.

In Kano, Nigeria’s second-largest city, Hamza Yousef, a tall, soft-spoken student, said he still hasn’t told his parents that he has become a Shiite. Yousef, 25, was born in the Saudi holy city of Mecca, where his family still lives. He’s now a student at the Almustafa International University, a branch of the main Islamic university based in Qom, Iran, which has campuses in several countries, including South Africa and Mali.

The U.S. wants to punish Iran “out of spite,” said Yousef. “America is an enemy of Islam.”

Seated on the floor of the center he runs in a low-income neighborhood, Shiite cleric Sheikh Sanus Abdul-Qader pointed up to the pictures of top Iranian, Lebanese and Nigerian Shiite leaders hung on the wall above him. They included Khamenei and Hezbollah leader Nasrallah.

“We consider them heroes who strive to help humankind and symbols of humanity,” Abdul-Qader said, as giggling children filled jerry cans with water from the center’s spigot on the dark street outside.

Did he think the U.S., with all its might, would prevail in any confrontation with Iran? “Iran will be steadfast if there’s a war,” said Abdul-Qader. “The strong always prevail.”